U.S. markets may rally once more before slumping for the subsequent six to 18 months, according to a research note by Nomura Strategist Bob Janjuah.
"If I look out three to six months, I am open to the idea of one last parabolic spike higher in risk-on markets," wrote Janjuah, who is known for his ultra-bearish views.
"I think we will eventually get fiscal and debt ceiling fudges in the U.S. Of course long-term credible solutions are needed… but in the interim, the knee jerk reaction of markets to fiscal/debt ceiling fudges will likely be positive."
Janjuah said the market rally could prove sharp enough to push the S&P 500 to 1,500 points. The S&P traded at 1,382.25 points on Tuesday, and has gained 9.32 percent year-to-date.
Janjuah's views concur with those of Ken Kamen, president of Mercadien Asset Management, who told CNBC on Tuesday that investors should position for a market rally on the resolution of the fiscal cliff problem. (Read More: What Is The Fiscal Cliff?)
"I am very optimistic that while we will have some gyration and pain in the short-run, maybe for the next three to six months, we are going to start moving towards an end-game," Kamen said. "That is what investors should position for."
However, Janjuah warned he remained "very bearish" over the longer-term, and forecast the S&P will slump throughout 2013, bottoming out in 2014 at around 800 points.
"I worry about excessive debt in the West, I worry about anemic growth globally, and I worry about the market's Pavlovian fixation on continued — but increasingly unsuccessful and non-credible — policy stimuli," he said.
Janjuah's outlook is even more negative than that of Marc Faber, another renowned bear. The Gloom, Boom and Doom report author forecast on Tuesday that the S&P will decline 20 percent from its September high of 1,470 points to around 1,176 points. (Read More: Prepare for a Massive Market Meltdown)
"I don't think markets are going down because of Greece, I don't think markets are going down because of the fiscal cliff — because there won't be a fiscal cliff," Faber told CNBC.
"The market is going down because corporate profits will begin to disappoint and the global economy will hardly grow next year, or even contract."
Faber cited tech giant Apple, as an example of a company whose disappointing earnings have caused its stock to fall 20 percent from its September highs. On Tuesday, Apple shares were trading at $547.64 on the Nasdaq.
— By CNBC.com's Katy Barnato